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A welding procedure is being qualified for the welding of A709 grade 36 plates for cyclically loaded structures. Assuming this structure was for the construction of high way bridge. The welding process is SMAW, and the welding configuration is a single V-groove weld with a steel backing. The thickness of the test plate is 15.9 inches. The plate is welded in the vertical position.

Q:- What is the required electrode classification for this qualification?